CI/CD about gtiff2tiles

[Gigas002]

Appveyor changelog can be found here. I don't think they'll add .net 5.0 support on windows before stable release of .net 5.0.

[Gigas002]

.net 5.0 available through vs2019 preview for windows and currently runs on rc builds. Waiting for stable release I guess...
https://www.appveyor.com/blog/

[Gigas002]

Nah it's not worth it. I already have windows builds and tests on github, it's kind of painful to implement it on appveyor without running tests and deploy afterwards.

[Gigas002]

Even though VS dotnet on appveyor has been updated, ubuntu's dotnet version is still in preview.3 state. Waiting for this issue to resolve.

[Gigas002]

Since I need to publish WPF app as well, it's probably a good idea to switch deploy environment to VS2019 from Ubuntu2004 on appveyor.

[Gigas002]

Multiple issues with publishing from appveyor:

1. Ubuntu2004 -- can't add linux console app to zip archive (even though win app adds correctly, see older builds)
2. Visual Studio 2019 (Windows) -- can't upload .zip assets to GitHub releases (broken authorization)

[Gigas002]

Windows build, tests and deploy is fixed, but the problem with linux's deploy to GitHub releases remains.

[Gigas002]

Fixed.

[Gigas002]

Wanted to move artifacts creation from after_tests stage to before_deploy in appveyor.yml, but it breaks CI. The point of this change is not to build artifacts on PRs, cause it's costing lots of time.
But judging by this issue, it's not possible (on appveyor).